With refrence to Michael Roland's answer, I am facing problems in changing the key of a Mifare Classic 4K card. I want to do the personalization of NFC cards using NFC reader ACR122U.
I have followed the steps defined in this answer, and successfully read and write the sector trailer block 11 (by reading I got the 2 access bytes and 1 general purpose byte), as
00 00 00 00 00 7F 07 88 40 00 00 00 00 00
Using these access bytes and the new keys KeyA (D6 DF 20 AE AE BC) and KeyB (D6 DF 20 AE AE BC), I generate 16 byte (D6 DF 20 AE AE BC ...), along with access bytes to change the sector keys. I.e. write to block 11 with following 16 bytes:
D6 DF 20 AE AE BC 7F 07 88 40 D6 DF 20 AE AE BC
The write command thus becomes
FF D6 00 11 10 D6 DF 20 AE AE BC 7F 07 88 40 D6 DF 20 AE AE BC
The command executed successfully but when I authenticated block 8 (1st block of same sector), using Key B (0x61) and key (1 or 0), the authentication failed and returns 0x63. Which means sector 2 becomes inaccessible.
Also after then read and write to that sector failed.
Also Android App NFCTagInfo shows following
Data (US-ASCII), Shows Sector 2: Read Failed!
Access Conditions : Sector 2 (Could not read access conditions!)
